建筑外文翻译---研究古建筑的三维重建方法.docx

附录a research on method of 3d reconstruction of ancient architecture (nanputuo temple) 10- 9 -abstractin this paper, regarding the great majesty hall of the nanputuo temple as a virtual modeling object, the research on the new technology of 3d reconstruction of the ancient architecture has been done, in which 3ds max and multigen creator were applied. the conflict was solved between precision and the amount of data existing in the process of 3d modeling virtual ancient architecture. the practical project has proved that the ancient architecture model made in this way has gotten living effect in roaming system, at the mean time it satisfies the data demand of real-time rendering. keyword： virtual reality (vr), ancient architecture protection, 3ds max, multigen creator1. introductionvirtual reality is a new man-machine interface. it provides users (participants) with satisfactory immersed experience and multi-sensory channels, and attempts to seek the best way of man-machine communication. using the virtual reality technology to realize the representation of ancient architecture is the innovation of architectural illustrational tools, and it is one of the hot topics of the present research. the lifelike computer modeling can not only demonstrate the profound cultural details of chinese ancient architectures, but have practical significance to the protection of ancient architectures in form of archives, therefore it was applied more widely than the traditional physical model. the modeling fidelity and rapid real-time data rendering are the foundations of realizing virtual reality desktop system. the project xiamen nanputuo temple virtual roaming system required that virtual scenes could reach a balance between the quality image and the speed of the rendering, and prescribed strictly the degree of accuracy and detail of every architecture. it controlled the amount of data as possible as we can on the basis of fine modeling. regarding the great majesty hall of the nanputuo temple as virtual modeling object, using the modeling method of 3ds max and multigen creator, the paper carried on beneficial discussion to the application of the technology in geometry modeling of ancient architectures. 2. chinese ancient architectures featuresin this paper, the virtual modeling object of the great majesty hall belong to imitation qing-dynasty ancient architectures. it followed the ancient chinese architecture major characteristics generally summarized as follows:(1) the most significant characteristic of ancient chinese architecture make full use of timber framework. wooden posts, beams, lintels and joists make up the framework of a house. walls serve as the separation of rooms without bearing the weight of the whole house, which is unique to china. as a famous saying goes, chinese houses will still stand when their walls collapse. the specialty of wood requires antisepsis methods to be adopted, thus develops into chinese own architectural painting decoration. (2) colored glaze roofs, windows with exquisite applique design and beautiful flower patterns on wooden pillars reflect the high-level of the craftsmens handicraft and their rich imagination. (3) the layout of a courtyard complex is also unique to china. the main structure is located on the central axis of a court while less-important structures are located to the left and right. the whole layout is symmetrical. 3. comparison of 3ds max and multigen creator in modeling of single complex architecture, fineness and fidelity, 3ds max has more advantages more multigen creator. 3ds max provides the polygon modeling, lofting, face modeling, nurbs face modeling, and other convenient and effective modeling method. it has a better ability of special effect processing and rendering. using 3ds max you can determine precisely the size and the position of the model. after modeling, you can modify each component according to the actual need at any moment. although 3ds max describes the objects details vividly, the large amount of the data of modeling cannot meet the need of real-time rendering. compared with 3ds max, multigen creator has less amount of modeling data. multigen creator has the real-time functions of polygon culling 、logic culling 、priority drawing 、binary separating plane and so on. openflight is the database format of creator. it uses hierarchical structure of nodes to describe the database, so as to inform the image generator when and how to render real-time 3d scenes. although creator generates file on the small volume data, and has a rapid rendering speed, it cannot be comparable to 3ds max in fine modeling of single architecture. therefore, in fine modeling of complex ancient architectures, the best way is to model single architecture in 3ds max firstly, then import it to multigen creator for simplification, and use key technologies such as lod, to satisfy the data demand of real-time rendering. 4. modeling processes using 3ds max and multigen creator in the actual construction process of ancient architecture, the components are divided into the following five levels: column base level、fitment level 、tou-kung level、beam frame level and roof level. each level comprises many timber components. these timber components not only have various shapes, but also have large amounts. therefore, the modeling method of taking the technology of integration of 3ds max and multigen creator is more suitable for the modeling requirements of chinese ancient architectures. figure 1 shows the flow chart of using the technology of integration of 3ds max and multigen creator to model the great majesty hall. figure 1. flow chart of modeling the great majesty hall4.1 preparing data data preparation is the key to modeling; it will have a direct impact on the quality of model. the model of the great majesty hall in this paper takes on the field survey and digital photos as the data basis, then the architectural plan is drawn in auto cad and saved as *.dwg. 4.2 making texturescollect the texture materials of the great majesty hall, then make the texture mapping needed for modeling through making them directly or processing digital photos by image processing softwares such as photoshop. substituting the 3d model for texture mapping to demonstrate the architectural details can not only represent the architectural feature of ancient architectures realistically, but also reduce the data amount and complexity of the model. 4.3 using 3ds max for modeling ancient architectureaccording to the structural characteristics of ancient architectures and 3ds max modeling principles, model the great majesty hall in the order of from bottom to top, from local to whole, from coarse to fine. specific steps include: (1) extract the needed actuality drawing of architecture from auto cad. then save the extracted local drawing as a new dwg file. all these were done to avoid reducing the computers running rate or even computers deadlock resulting from the so large imported dwg file. (2) 3ds max uses import order to import the saved dwg file. since the imported base map has the elevation value, it is not convenient to observe. so we need to compress the height of z direction in top view to 0. (3) using data imported just now, establish the 3d model in 3ds max. as a result of the unique structure feature, modeling must be in order: firstly, stylobate， because stylobate is the support of upper weight and the basis of the whole architecture; secondly, column, wall and beam frame ， lastly, the roof. after the establishment of the chief structure of the great majesty hall is completed，it is modeling of the local parts, such as the doors and windows ,banisters, wenshou, sill and so on of the great majesty hall. (4) carry on the texture mapping for 3d model. the choices of texture materials are very important to the lifelike demonstration of the architecture. high resolution textures could produce lifelike visual effects but simultaneously also increase the burden of scene demonstration. using the appropriate resolution textures and materials can reduce the geometric details of the model and at the same time produce better visual effects. after the modeling completes, process the photos taken from the spot by high resolution digital camera and then save them as texture pictures of appropriate size. use appropriate mapping methods and coordinates in 3ds max to implement the mapping to every component of the architecture, such as use the uvw mapping order in modifier to modify the mapping coordinate. simultaneously to reduce the data amounts of the textures, use the repeated mapping method as far as possible in mapping. figure 2 shows the completed 3d model of the great majesty hall. figure 2. 3d model of the great majesty hall4.4 importing model to creator for simplification importing model from 3ds max to creator for model simplification needs three steps: (1) importing model. import the 3ds file exported from 3ds max to creator. then the texture path of the model loses. so you need to designate a new texture path. the latter path should be a relative path which is the same to the models path. this can increase the flexibility of model path. (2) organizing the structure of database. the database of the 3ds files does not have the hierarchical structure; all objects are placed under the identical father node. so we should re-organize the database according to the primary and secondary of different parts of the ancient architecture model. this will not only facilitate the selection operation on model in the process of modeling, but also improve the graphic rendering speed and avoid some drawing errors in the scene rendering and browsing. (3) simplifying model. that is, under the premise of not affecting the models appearance, to display the model with few data and eliminate the redundant data. the exported 3ds files save faces in form of triangle, but the creator save faces in form of polygon. for simplification, you can use the combine face tool in creator to merge the coplanar triangles to a polygonal face. this may reduce the polygon amount largely. in addition, the application of instance can simplify the model. often, the model of a ancient architecture includes a number of same components, such as toukung 、posts, beams and so on. in the modeling process, you can use the technology of instance, copy the component to other positions. so that the database will not establish the node of the same model repeatedly. this can save the memory space greatly. finally, some invisible faces can be deleted directly, such as the underside of the model and adjacent faces between the neighboring components. 4.5 making lod model lod（level of details）is a model management method saving objects by different detail . the same scene or the object in the scene may call the model of different detail level according to the need of drawing scene. the higher the lod models detail degree is , the finer its model is, the bigger the data amount is; the lower the detail degree is , the less simple its scene or model is, the smaller the data amount is. generally, the model with low level of details is adopted in remote distance observation. it does not affect the third dimension; when short distance observation, the model with high level of details is adopted, and you may see a very fine model . there are many methods for establishing lod models. in the paper, we use two, deletion method and grabbing picture method . the deletion method is to delete the detail parts of the model and preserve the main parts. it is suitable for the components of fitment level of the architecture. but the disadvantage of the method is the difficulty to minimize the models data amount. the grabbing picture method can simplify some faces the model needs to display, such as the windows of the architecture, their structures are very complicated. this can be done by grabbing picture method. the grabbing picture method is to grab image using the function of capturing screen, then deal with it for texture, and finally associate the texture with a whole face to demonstrate the face of the model. the faces of the completed junior lod model should not exceed one third of the senior lod model. figure 3 shows the three-level lod model using deletion method and grabbing picture method. lod model of level 1lod model of level 2lod model of level 3figure 3. lod models of three levelsthe lod model of level 1 showed in figure 3 has 3874 faces. but the model showed in figure 2 has 10412 faces. it is obvious that the data amount drops largely, but there is no obvious visual effects difference. table 1. three-level lod models precision comparison tableseen from the data in table 1, the three-level lod model established by deletion method and grabbing picture method can reduce the face number effectively. it lays the foundation for the completion of nanputuo temple virtual roaming system. 5. conclusions this paper simplified the huge data model in 3ds max to certain degree using the key technologies of powerful 3d data organizing function, instance, multilevel detail modeling and so on in mutligen creator, so that it satisfies the demand of real-time rendering. the technology reduced the data amount to a great degree, and has good demonstration effect in the project. at the same time, the feasibility and practicability of taking 3ds max and mutligen creator integration for the 3d reconstruction of ancient architectures are proved. 附录b研究古建筑的三维重建方法(南普陀寺)摘要在本文中，以庄严伟岸的南普陀寺大雄宝殿作为一个虚拟建模对象，研究三维重建的新技术的古代建筑。该研究已经在3ds max与multigen creator中被应用过。存在于虚拟古代建筑3d建模过程中的数据资料的精度与数量之间的冲突已经得到了很好的解决。工程实践证明，古代建筑模型用这样的方式制作是在漫游系统效果方面受到了生活的影响，同时它满足了实时渲染的数据需求。关键词：虚拟现实(vr)；古代建筑保护；3ds max；multigen creator。1、 介绍 虚拟现实是一种新型人机联系装置。它给用户与参与者提供了令人满意的沉浸体验和多感知通道，并试图寻求人机交互的最佳方式。利用虚拟现实技术来实现古建筑的表现是建筑例证工具的新方法，而且它是目前研究的热点问题。计算机模拟的逼真不仅能够展示中国的古代建筑深厚的文化底蕴，还在以档案的形式上保护古代建筑的法国难免有这现实意义。因此，这种技术将会比传统的物理模型拥有更加广泛的应用。建模的逼真度和快速实时数据的渲染是实现虚拟现实桌面系统的基础。“厦门南普陀寺虚拟漫游系统”的项目要求各个虚拟场景可以在产品的品质形象与提高渲染速度之间达到平衡，严格规定精确程度和每一个结构的细节。它控制了大量的数据，我们可以尽可能地在此基础上精细建模。本文中，以庄严伟岸的南普陀寺大雄宝殿作为一个虚拟建模对象，应用3ds max与multigen creator建模方式进行了研究，并对这种技术在几何建模的古代建筑的应用进行了有益的探讨。2、 中国古代建筑的特点在本文中，大雄宝殿的虚拟建模对象属于模仿清朝时期的古建筑。随之而来的是中国古代建筑的主要特征，一般概括如下：(1) 中国古代建筑的最重要的特征就是充分利用木材的框架。木制的柱子、横梁、门楣和托梁构成了整个房子的框架。墙体只是充当房间的间隔，而没有支撑整个房子的重量,这一特点是中国特有的。就像一句名言所说：“中国的房子依然会挺立，即便墙壁坍塌。”木材的特点是需要采取防腐措施,从而发展成中国自己的建筑绘画装饰。(2)色釉的屋顶、装有精湛的贴花设计的窗户和刻有漂亮花朵图案的木柱子反映了高层次的工匠工艺品及其丰富的想象力。(3)庭院复杂的布局也是中国特有的，主要结构是位于庭院的正中央而次要的结构则是位于庭院的左和右两侧，整个布局是对称的。3、 3ds max与multigen creator的对比在单一复杂的建筑、精细化、保真度的建模方面，3ds max更具有优越性虚拟现实效果更好。3ds max中提供了多边形建模、放样、平面建模、nurbs平面建模和其他方便有效的建模方法，它有更好的处理特效加工和渲染的能力。利用3ds max你可以精确地定位模型的大小与位置。建模之后，你可以根据实际的需要随时修改每个部分。尽管3ds max生动地描述了对象的细节，但是还有大量的建模数据不能满足实时渲染的需要。与3ds max相比，multigen拥有更少的建模数据。multigen creator拥有多边形扑杀、逻辑扑杀、优先图纸、二进制分离平面等实时功能。openflight是creator的数据库格式，它采用节点的层级结构来描述数据库，以便通知图像发电机何时还有如何提供实时的3d场景。虽然creator是基于少量数据产生文件的，并拥有快速的渲染速度，但是在单一建筑的精细建模方面，它不能与3ds max相比较。因此，在复杂的古代建筑的精细建模中，最好的办法就是首先用3ds max进行单建筑模型的建模，然后导入到multigen creator中进行简化，并利用lod等关键技术，以满足实时渲染的数据需求。4、 使用3ds max和multigen creator的建模进程在实际的建筑施工进程中，这些组件是被分成如下五层的：柱基础层，装修层，透空层，梁框架层和屋顶层。每一层都有许多木材组件。这些木材不仅形状不同，而且数量很大。因此，采用了3ds max与multigen creator中集成技术的建模方式，更适合于中国古代建筑的建模要求。图1显示的流程图，就是应用3ds max与multigen creator中集成技术来创建大雄宝殿模型的流程图。图1创建大雄宝殿模型的流程图4.1准备数据数据准备是建模的关键，它会直接影响建模的质量。在本文中的大雄宝殿的模型是以实地考察和数码照片作为数据基础的，然后，将建筑方案在autocad中绘制并保存为“*dwg”格式。4.2创建材质收集大雄宝殿的材质,然后直接将需要的材质贴图附给模型，或者使用图像处理软件如photoshop对数码照片处理。使用展现建筑细节的材质贴图取代三维模型,不仅可以真实地表现出古代建筑的建筑特点,而且还可以减少模型的复杂度与数据量。4.3使用3ds max创建古代建筑模型根据古代建筑的结构特点和3ds max的建模法则，对大雄宝殿的建模应该按照从下到上、从局部到整体、从粗到细的次序。具体步骤如下：(1)从autocad中导出所需的建筑现状图，然后将提取出的局部图保存为新的dwg文件。这样的做法是为了避免因导入如此大的dwg文件而引起计算机运行效率降低甚至电脑僵局。(2)在3ds max中选择“导入”选项，导入保存的dwg文件。由于导入的工作草图中包含高度值，不方便观察，所以我们需要在顶视图中压缩z轴的高度为0。(3)使用刚导入的数据